China's fine chemical industry has experienced soaring development and contributed enormously to its national economy since it adopted reform and opening-up policy. However, the wastewater discharged by this industry is complicatedly constituted, highly concentrated and toxic, deep in color and hard to be biodegradated. It has caused severe pollution to the ecosystem and the environment as a whole. Therefore, it is urgent to find appropriate methods for treating this kind of wastewater.
Biotechnology is the most economical way in wastewater treatment, however, it may leave residual metabolites of microorganisms and their decomposition products, toxic substances that cannot be degradated by microorganisms and various inorganics in the wastewater, which requires a deep treatment procedure to ensure that the discharged wastewater reaches the state environmental standards. Resin adsorption is one of the most widely used technologies in the wastewater deep treatment field. This method has such advantages as high adsorption capacity, desirable mechanical properties and capability of recycled use. However, when adopting resin adsorption to treat biochemical effluent, there would be a large amount of desorption liquid, which is complicatedly constituted, highly concentrated and toxic, deep in color and hard to be biodegradated. These properties make treatment of desorption liquid a great challenge widely recognized in the environmental protection field, and restrict the application of resin in various industries as well. Therefore, it is very urgent to find out a cheaper and more efficient method for treating the desorption liquid.
Currently, the most common methods for treating the desorption liquid include enhanced coagulation, catalytic oxidation, catalytic reduction and membrane filtration. The coagulation method presents great efficiency in removing hydrophobic large molecules, but its performance in removing polar organic small molecules is limited. This means the desorption liquid treated with this method cannot directly meet the discharge standards. In addition, this method also results in large consumption of coagulating agent and a large amount of sludge. The catalytic oxidation method is essentially a kind of advanced oxidation process. It presents many advantages such as complete degradation, no secondary pollution, low energy and raw material consumption; however, the Fenton oxidation method requires precise control of pH value while the ozone oxidation requires large construction investment and high operation expenses. Insofar as the membrane filtration method is concerned, the membrane adopted therein presents such defects as high cost in manufacturing and being easy to be contaminated. Therefore, separate exploitation of above-mentioned methods can hardly realize economical and efficient treatment of desorption liquid; a combined method that integrates two or more methods is of great necessity.